This invention relates generally to endobronchial tubes for insertion through the mouth or nasal passages of a patient to facilitate artificial ventilation of the respiratory system. More particularly, this invention relates to endobronchial tubes with a single primary bore or lumen and multiple balloon cuffs for selective ventilation of one or both lungs.
It is a common practice to provide human medical patients with artificial ventilation during surgery or in emergency situations. For example, accident victims will frequently require CPR or intubation by a paramedic in an emergency vehicle or by an anesthesiologist in an operating room. In such situations, intubation is accomplished by insertion of an endotracheal tube through the patient's mouth or nasal passages into the airway passage. Such devices have generally comprised a relatively pliable tube with means for connecting it to a respirator or other air supply mechanism for introduction of air into the lungs. An improvement to endotracheal tubes includes an inflatable-deflatable bag-like structure or balloon "cuff" around the exterior of the tube. The balloon cuff is conventionally located in a position along the endotracheal tube to engage the inner wall of the pharynx, larynx, or trachea depending upon the specific endotracheal tube design. When the tube is in place, the cuff is inflated and forms an air tight seal between the tube and the surrounding body tissue to prevent the escape of air pumped from the respirator into the lungs.
Both single lumen and double lumen endotracheal tubes are known. Typically, a single lumen endotracheal tube is an elongated tube that extends into the trachea of a patient upon intubation and includes one inflatable balloon cuff near its distal end. Commonly, the double lumen endotracheal tube is referred to as an endobronchial tube and, in addition to one lumen which extends to the trachea, has a second longer lumen which extends into the bronchus of a patient upon intubation. Typically, the double lumen endotracheal tube or endobronchial tube includes two inflatable balloon cuffs. The so-called double lumen endobronchial tubes, such as the well known "Carlens" and "Robertshaw" tubes, allow for independent control of each lung through the separate lumina. One bronchus may be blocked by occluding one of the lumina at a position external to the patient, in order to isolate a particular lung.
The balloon cuffs are thin walled, high volume, and low pressure chambers or vessels which are designed not to compromise the blood flow in the tracheal or bronchial wall when inflated. Balloon cuffs are inflated by detachable syringes that are connected to smaller lumina or channels at the proximal end of the endotracheal tube. The seals formed by the inflated cuffs preclude the air that has been forced into the patient's lungs from escaping through the trachea or bronchus. Additionally, the seals formed by the inflated cuffs provide a barrier to the flow of blood and secretions.
The so-called double lumen endobronchial tubes offer the anesthesiologist the ability to insufflate selectively either the right or left lung or both lungs as required. However, in order to minimize damage to the tissue on the tracheal wall, the overall outer diameter of both single and double lumen endobronchial tubes is limited to approximately 1.2 cm. For this reason, the inner diameter of each lumen of a double lumen endobronchial tube is by necessity smaller than the inner diameter of a single lumen endotracheal tube. As a result, the inner diameter of the single lumen endotracheal tube can typically be no more than about 7.5 mm; whereas, the inner diameter of each lumen in a double lumen endobronchial tube is limited to a maximum of approximately 3.5 mm.
Another endobronchial tube design which offers the anesthesiologist the capability to insufflate one or both lungs of a patient is shown in U.S. Pat. No. 4,248,221. The endobronchial tube disclosed in that patent includes a single lumen with three balloon cuffs. Two of the cuffs are located on the outer surface of the tube and the third is located within the lumen between two outlet ports in the tube. By positioning the tube of U.S. Pat. No. 4,248,221 in the trachea and one mainstem bronchus of the patient and selectively inflating the individual balloon cuffs, one or both of the patient's lungs may be insufflated. However, in that one of the balloon cuffs is internal to the lumen, access through the lumen is blocked.
The larger lumen provided in a single lumen endotracheal tube having no internal lumen balloon cuffs affords the anesthesiologist access for other instrumentation through the lumen as required. The removal of mucous, the injection of medication, or the insertion of fiber optic instrumentation for viewing within the endotracheal tube are examples of the additional instrumentation capability which is afforded by a single lumen tube. The ability to insert fiber optic instrumentation through the tube significantly aids the anesthesiologist during intubation to accurately determine if the endobronchial tube is correctly positioned within the trachea and bronchus of the patient. These capabilities are restricted, if not prohibited, in the double lumen endobronchial tubes which by necessity have more narrow inner diameter passages and afford less access through the tubes by the anesthesiologist for the probes and instrumentation described.
Although the use of various double cuff arrangements with double lumen endobronchial tubes offer advantages which are not present in single lumen endotracheal tubes, namely the capability to insufflate one or both lungs from a single tube, these advantages cannot be provided with currently available single lumen tubes. However, the use of single lumen tubes offers the advantages of additional instrumentation capability through the larger lumen tube which cannot be provided with current double lumen tubes. For these and other reasons both prior art single and double lumen tubes are not fully satisfactory.